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"They Don’t Make ‘Em Like They Used To" Wrong. The explanation why the bulb still holds is very simple. By turning it off and on again, the tungsten contracts a

by Kenji 12y ago

"They Don’t Make ‘Em Like They Used To" Wrong. The explanation why the bulb still holds is very simple. By turning it off and on again, the tungsten contracts and expands. That is why light bulbs break after a certain amount of time. If you keep the bulb lit or turned off, it won't break. In this case, the bulb was lit with the exception of very few power outages. Also mentioned in the article: "Katz also adds that the bulb’s age could be, in part, contributed to the fact that it hasn’t been turned off and on a whole lot -- a process which is more exhausting on a bulb than letting it run continuously (the filament needs to reheat itself, much like a car’s engine)."

spacecadet 12y ago
+1 This is exactly how I understood it to work... "has been proclaimed the “Eternal Light” by General Electric experts and physicists around the world." What experts and physicists?
coryrc 12y ago
Not so much; it's operating far under the level of light it could put out and at atrocious efficiency. As said in the article: "Modern bulbs, she explains, use thinner tungsten filaments that put out more light (40 to 200 watts) burn hotter, and are therefore taxed more rigorously than older bulbs like the Shelby" With semiconductors, the rule of thumb is an increase of 10 Kelvin halves the lifetime of the part. Considering this bulb is running several hundred Kelvin below modern bulbs, it isn't surprising it lasts. Run a modern 60W lightbulb at 30Vac and it'll last just as long too, but put out so little light as to be near useless (like this bulb).
- femto 12y ago
  Another common example is the light bulb behind a typical doorbell button. For example, the one on my parent's house is a 12V bulb, with the voltage turned down so it only produces a glimmer of light, enough to locate the button at night. It also runs continuously. So far it's clocked up 40 years and will probably outlast the structure of the brick wall it is attached to.
- perrylaj 12y ago
  You pretty much nailed it. I lived down the street from this lightbulb as a kid and never heard of it until it became a phenomenon on the web. It should be said that they intentionally run it dim in order to prevent burnout. Didn't read the full article, but I'm guessing they mentioned the lightbulb also has its own UPS to deal with power outages/surges. Unless I'm forgetting my P-Chem (possible, it wasn't a favorite subject), the 10 kelvin/halving lifetime loosely holds true for most chemical reactions that occur out of extremes -- e.g. that relationship holds true for most reactions that naturally occur on our planet. I still find that to be one of nature's neat factoids.
- jloughry 12y ago
  If you're at all interested in this topic, I can't recommend highly enough a little book by Tony Kordyban, Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong. (The sequel, More Hot Air, is good too). The author makes the case, in Chapter 30, that those numbers, which came from MIL-HDBK-217, were pulled out of somebody's hat at a time when semiconductor reliability rates were changing rapidly due to process improvements, and probably don't have much validity any more. When actual reliability rates were compared to prediction and measured temperatures, there was no correlation. These books are great. Refs: [1] Tony Kordyban. Hot Air Rises and Heat Sinks. New York: ASME Press, 1998. ISBN 0-7918-0074-1 [2] ---. More Hot Air. New York: The American Society of Mechanical Engineers, 2005. ISBN 0-7918-0223-X
droopyEyelids 12y ago
We need a word to describe the feeling of seeing the most popular, agreed-upon explanation somewhere, and knowing it's wrong.
- noonespecial 12y ago
  If it exists, its German and 14 syllables long. I submit Rechtgefühleinsamkeit as a candidate.
  - noonespecial 12y ago
    Oops. I rescind. That would be the feeling of discovering you're the only Republican in a room full of Democrats!
crishoj 12y ago
Not completely wrong, they actually do not make them like they used to. There is evidence that lightbulb manufacturers forged a coalition and agreed to artificially shorten then mean lifespan of their products, a classic example of planned obsolescence. For an entertaining walk through, watch the documentary The Lightbulb Conspiracy.
- StillBored 12y ago
  Apparently, its continuing with LED's as well, as I've just had the 3rd "burn out" yesterday. I'm too lazy to count the number of bulbs (~20) and compute my own personal failure rates and expected lifetimes, but my seat of the pants estimates are that the 10 year lifespans are a bit optimistic, given that all three died in under a year (three different manufactures too). The ones that died were in open fixtures, so heat shouldn't be a problem either. The first couple I took apart to determine if the LEDs were the problem (they weren't, the power supplies are the weak link), this one I'm going to send back to Cree to see if they actually honor the 10 year warranty, on my 3 month old bulb.
loupgarou21 12y ago
I know personal experience doesn't exactly count as rigorous scientific study, but I do have one light in my house that I literally never turn off in my kitchen. No automatic switch or anything, it burns 24/7/365. It burns out roughly every 3 years (26,000 hours, pretty damned good, right.) That bulb is subject to various other environmental factors that will reduce it's lifespan (vibration and high heat.) I've forgotten my point now, but I think it boils down to, a single factor, such as power cycling, isn't likely going to be the only reason a bulb doesn't last as long. A lot of factors play into it, including both environment and manufacturing.
- adventured 12y ago
  Can definitely confirm this effect. Had a regular bulb in a standing lamp that was pointing upward toward a corner of my home office, that I never turned off. It lasted five years of being on 24/7. The other bulbs used in it (the lamp has three light inserts) have also lasted incredibly long durations (typically 2 to 3 years).
ekianjo 12y ago
I have seen numerous light bulbs in my house break while being lit, and not just when switching them on and off. I am not very convinced by your explanation.
- bagels 12y ago
  http://en.wikipedia.org/wiki/Fatigue_(material) http://en.wikipedia.org/wiki/Fatigue_(material) The idea is: Turn it on, metal expands (thermal expansion) Turn it off, metal contracts This is the repeatedly applied load, hence eventual material failure. Also, the hotter you run the bulb, the more tungsten evaporates.

by Kenji 12y ago

spacecadet 12y ago

+1 This is exactly how I understood it to work... "has been proclaimed the “Eternal Light” by General Electric experts and physicists around the world." What experts and physicists?

coryrc 12y ago

Not so much; it's operating far under the level of light it could put out and at atrocious efficiency. As said in the article: "Modern bulbs, she explains, use thinner tungsten filaments that put out more light (40 to 200 watts) burn hotter, and are therefore taxed more rigorously than older bulbs like the Shelby" With semiconductors, the rule of thumb is an increase of 10 Kelvin halves the lifetime of the part. Considering this bulb is running several hundred Kelvin below modern bulbs, it isn't surprising it lasts. Run a modern 60W lightbulb at 30Vac and it'll last just as long too, but put out so little light as to be near useless (like this bulb).

femto 12y ago
Another common example is the light bulb behind a typical doorbell button. For example, the one on my parent's house is a 12V bulb, with the voltage turned down so it only produces a glimmer of light, enough to locate the button at night. It also runs continuously. So far it's clocked up 40 years and will probably outlast the structure of the brick wall it is attached to.
perrylaj 12y ago
You pretty much nailed it. I lived down the street from this lightbulb as a kid and never heard of it until it became a phenomenon on the web. It should be said that they intentionally run it dim in order to prevent burnout. Didn't read the full article, but I'm guessing they mentioned the lightbulb also has its own UPS to deal with power outages/surges. Unless I'm forgetting my P-Chem (possible, it wasn't a favorite subject), the 10 kelvin/halving lifetime loosely holds true for most chemical reactions that occur out of extremes -- e.g. that relationship holds true for most reactions that naturally occur on our planet. I still find that to be one of nature's neat factoids.
jloughry 12y ago
If you're at all interested in this topic, I can't recommend highly enough a little book by Tony Kordyban, Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong. (The sequel, More Hot Air, is good too). The author makes the case, in Chapter 30, that those numbers, which came from MIL-HDBK-217, were pulled out of somebody's hat at a time when semiconductor reliability rates were changing rapidly due to process improvements, and probably don't have much validity any more. When actual reliability rates were compared to prediction and measured temperatures, there was no correlation. These books are great. Refs: [1] Tony Kordyban. Hot Air Rises and Heat Sinks. New York: ASME Press, 1998. ISBN 0-7918-0074-1 [2] ---. More Hot Air. New York: The American Society of Mechanical Engineers, 2005. ISBN 0-7918-0223-X

droopyEyelids 12y ago

We need a word to describe the feeling of seeing the most popular, agreed-upon explanation somewhere, and knowing it's wrong.

noonespecial 12y ago
If it exists, its German and 14 syllables long. I submit Rechtgefühleinsamkeit as a candidate.
- noonespecial 12y ago
  Oops. I rescind. That would be the feeling of discovering you're the only Republican in a room full of Democrats!

crishoj 12y ago

Not completely wrong, they actually do not make them like they used to. There is evidence that lightbulb manufacturers forged a coalition and agreed to artificially shorten then mean lifespan of their products, a classic example of planned obsolescence. For an entertaining walk through, watch the documentary The Lightbulb Conspiracy.

StillBored 12y ago
Apparently, its continuing with LED's as well, as I've just had the 3rd "burn out" yesterday. I'm too lazy to count the number of bulbs (~20) and compute my own personal failure rates and expected lifetimes, but my seat of the pants estimates are that the 10 year lifespans are a bit optimistic, given that all three died in under a year (three different manufactures too). The ones that died were in open fixtures, so heat shouldn't be a problem either. The first couple I took apart to determine if the LEDs were the problem (they weren't, the power supplies are the weak link), this one I'm going to send back to Cree to see if they actually honor the 10 year warranty, on my 3 month old bulb.

loupgarou21 12y ago

I know personal experience doesn't exactly count as rigorous scientific study, but I do have one light in my house that I literally never turn off in my kitchen. No automatic switch or anything, it burns 24/7/365. It burns out roughly every 3 years (26,000 hours, pretty damned good, right.) That bulb is subject to various other environmental factors that will reduce it's lifespan (vibration and high heat.) I've forgotten my point now, but I think it boils down to, a single factor, such as power cycling, isn't likely going to be the only reason a bulb doesn't last as long. A lot of factors play into it, including both environment and manufacturing.

adventured 12y ago
Can definitely confirm this effect. Had a regular bulb in a standing lamp that was pointing upward toward a corner of my home office, that I never turned off. It lasted five years of being on 24/7. The other bulbs used in it (the lamp has three light inserts) have also lasted incredibly long durations (typically 2 to 3 years).

ekianjo 12y ago

I have seen numerous light bulbs in my house break while being lit, and not just when switching them on and off. I am not very convinced by your explanation.

bagels 12y ago
http://en.wikipedia.org/wiki/Fatigue_(material) http://en.wikipedia.org/wiki/Fatigue_(material) The idea is: Turn it on, metal expands (thermal expansion) Turn it off, metal contracts This is the repeatedly applied load, hence eventual material failure. Also, the hotter you run the bulb, the more tungsten evaporates.